Buggy code:
public class MailerModel extends AbstractTestElement implements Serializable { private static final long serialVersionUID = 233L ; private static final Logger log = LoggingManager . getLoggerForClass ( ) ; private static final String MAIL_SMTP_HOST = "mail.smtp.host" ; private long failureCount = 0 ; private long successCount = 0 ; private boolean failureMsgSent = false ; private boolean siteDown = false ; private boolean successMsgSent = false ; private static final String FROM_KEY = "MailerModel.fromAddress" ; private static final String TO_KEY = "MailerModel.addressie" ; private static final String HOST_KEY = "MailerModel.smtpHost" ; private static final String SUCCESS_SUBJECT = "MailerModel.successSubject" ; private static final String FAILURE_SUBJECT = "MailerModel.failureSubject" ; private static final String FAILURE_LIMIT_KEY = "MailerModel.failureLimit" ; private static final String SUCCESS_LIMIT_KEY = "MailerModel.successLimit" ; private static final String DEFAULT_LIMIT = "2" ; private transient ChangeListener changeListener ; public MailerModel ( ) { } public void addChangeListener ( ChangeListener list ) { } @ Override public Object clone ( ) { } public void notifyChangeListeners ( ) { } public List < String > getAddressList ( ) { } public void add ( SampleResult sample ) { } public synchronized void add ( SampleResult sample , boolean sendMails ) { } @ Override public synchronized void clear ( ) { } @ Override public String toString ( ) { } public void sendMail ( String from , List < String > vEmails , String subject , String attText , String smtpHost ) throws MessagingException , AddressException { String host = smtpHost ; boolean debug = Boolean . valueOf ( host ) . booleanValue ( ) ; InternetAddress [ ] address = new InternetAddress [ vEmails . size ( ) ] ; for ( int k = 0 ; k < ( vEmails . size ( ) ) ; k ++ ) { <START_BUG> address [ k ] = new InternetAddress ( vEmails . get ( k ) . toString ( ) ) ; <END_BUG> } Properties props = new Properties ( ) ; props . put ( MailerModel . MAIL_SMTP_HOST , host ) ; Session session = Session . getDefaultInstance ( props , null ) ; props = session . getProperties ( ) ; if ( ! ( host . equalsIgnoreCase ( props . getProperty ( MailerModel . MAIL_SMTP_HOST ) ) ) ) { props . setProperty ( MailerModel . MAIL_SMTP_HOST , host ) ; } session . setDebug ( debug ) ; Message msg = new javax . mail . internet . MimeMessage ( session ) ; msg . setFrom ( new InternetAddress ( from ) ) ; msg . setRecipients ( TO , address ) ; msg . setSubject ( subject ) ; msg . setText ( attText ) ; Transport . send ( msg ) ; } public synchronized void sendTestMail ( ) throws MessagingException , AddressException { } public void setToAddress ( String str ) { } public void setFromAddress ( String str ) { } public void setSmtpHost ( String str ) { } public void setFailureSubject ( String str ) { } public void setSuccessSubject ( String str ) { } public void setSuccessLimit ( String limit ) { } public void setFailureLimit ( String limit ) { } public String getToAddress ( ) { } public String getFromAddress ( ) { } public String getSmtpHost ( ) { } public String getFailureSubject ( ) { } public String getSuccessSubject ( ) { } public long getSuccessLimit ( ) { } public long getSuccessCount ( ) { } public long getFailureLimit ( ) { } public long getFailureCount ( ) { } }

Fix:
address [ k ] = new InternetAddress ( vEmails . get ( k ) ) ;